San Francisco Syncope Rule (SFSR) Calculator
For Risk Stratification of Emergency Department Syncope Patients
The San Francisco Syncope Rule (SFSR) identifies patients with syncope who are at high risk for serious short-term outcomes. Check all criteria that apply to the patient.
San Francisco Syncope Rule Result
Clinical Interpretation & Disposition
Recommended Management:
About the San Francisco Syncope Rule
The SFSR is a validated clinical decision tool used in the Emergency Department to identify syncope patients at high risk for serious 30-day outcomes.
High-Risk Criteria (Any ONE qualifies):
- History of Congestive Heart Failure
- Shortness of Breath at time of event or presentation
- Hematocrit < 30%
- Triage Systolic BP < 90 mmHg
- Abnormal ECG (any finding other than normal sinus rhythm)
Clinical Decision Algorithm
HIGH-RISK (Any criterion positive): Hospital admission or extended observation for cardiac monitoring and further investigation.
LOW-RISK (All criteria negative): Consider safe discharge with appropriate follow-up.
Serious Outcomes Predicted by SFSR
The SFSR predicts the following serious outcomes within 30 days:
- Death
- Myocardial infarction
- Arrhythmia requiring intervention
- Pulmonary embolism
- Stroke
- Significant hemorrhage requiring transfusion
- Any condition requiring surgical intervention
- Readmission for related event
The San Francisco Syncope Rule is a set of criteria designed to help emergency physicians determine which patients who present with syncope or near-syncope need to be admitted to the hospital for further monitoring and workup. Its goal is to safely identify low-risk patients who can be discharged, while ensuring high-risk patients are not missed.
Detailed Breakdown
1. Clinical Context and Purpose
Syncope is a common emergency department presentation. The challenge is that while most causes are benign (e.g., vasovagal syncope), a small percentage are due to life-threatening conditions like arrhythmias, pulmonary embolism, or significant bleeding. The SFSR was developed to stratify this risk.
Its primary use is:
- Risk Stratification:Â To predict the risk of a serious outcome within 30 days of the syncopal event.
- Guide Disposition:Â To provide an evidence-based method for deciding between hospital admission and safe discharge.
- Resource Allocation:Â To help avoid unnecessary hospital admissions for low-risk patients.
2. The Rule: Criteria for High Risk
According to the SFSR, a patient is considered high-risk if any one of the following five factors is present:
| Risk Factor | Explanation |
|---|---|
| 1. History of Congestive Heart Failure | A known past medical history of CHF. |
| 2. Shortness of Breath (Dyspnea) | Patient reports dyspnea at the time of the syncopal event or presents with it. |
| 3. Hematocrit < 30% | Significant anemia identified on initial blood work. |
| 4. Triage Systolic BP < 90 mmHg | Low blood pressure recorded at the time of emergency department triage. |
| 5. Abnormal ECG | Any ECG finding that is not normal sinus rhythm. This includes: • New changes (e.g., ischemia, arrhythmia) • Non-sinus rhythm (e.g., atrial fibrillation, heart block) • Any significant abnormality (e.g., bundle branch block, ventricular ectopy) |
3. Interpretation and Clinical Application
- If ANY factor is present: The patient is considered high-risk. The recommendation is for hospital admission or an extended observation period for further cardiac monitoring and investigation.
- If NO factors are present: The patient is considered low-risk. The physician can confidently consider discharge with appropriate follow-up.
The rule has been validated to have a high sensitivity (around 96-98%), meaning it is very good at “catching” nearly all patients who will go on to have a serious outcome.
What Constitutes a “Serious Outcome”?
The SFSR was designed to predict the following serious outcomes within 30 days:
- Death
- Myocardial infarction (Heart attack)
- Arrhythmia (e.g., ventricular tachycardia, significant bradycardia)
- Pulmonary embolism
- Stroke
- Significant hemorrhage requiring transfusion
- Any condition requiring a procedure or surgery (e.g., pacemaker implantation)
- Readmission for a related event
Comparison with Other Syncope Rules
Other well-known syncope rules include:
- OESIL Score:Â Uses age >65, cardiovascular disease, syncope without prodrome, and abnormal ECG.
- ROSE Rule:Â A more recent rule that adds BNP (a heart failure biomarker) and rectal exam for occult bleeding.
The SFSR is particularly noted for its simplicity and high sensitivity.
Limitations and Criticisms
- Not Perfect Sensitivity:Â While high, the sensitivity is not 100%. Clinical judgment must always supersede the rule.
- Variable Specificity:Â The rule has relatively low specificity, meaning it may still flag some patients as high-risk who would have done well as outpatients. This is considered an acceptable trade-off for patient safety.
- Application:Â It is intended for use in the emergency department for syncope of likely cardiac or unknown cause. It may not be as useful for clearly situational or vasovagal syncope in young, healthy individuals.
- ECG Interpretation:Â The “abnormal ECG” criterion is broad and relies on the physician’s interpretation, which can introduce variability.
Summary
The San Francisco Syncope Rule is a validated, simple, and highly sensitive clinical tool that uses five key variables (CHF, SOB, Low Hct, Low SBP, Abnormal ECG) to identify syncope patients at high risk for serious short-term outcomes. Its primary value lies in helping emergency physicians make safe disposition decisions, ensuring that high-risk patients receive the inpatient care they need while allowing low-risk patients to avoid unnecessary hospitalization.
Disclaimer: This information is for educational purposes only. The management of syncope is complex and must be directed by qualified healthcare professionals using their clinical judgment.
